TITLE: GCN CIRCULAR NUMBER: 15776 SUBJECT: GRB 140129B: MASTER OT early light curve DATE: 14/01/30 08:54:54 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.A.Poleshchuk, O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Chuvalaev, Irkutsk State University D.Denisenko, E. Gorbovskoy, V. Lipunov, D.Kuvshinov, N.Tyurina, N.Shatskiy, P.Balanutsa, A.Kuznetsov, V.Kornilov, V.V.Chazov Lomonosov Moscow State University, Sternberg Astronomical Institute V.Yurkov, Yu.Sergienko, D.Varda, E.Sinyakov Blagoveschensk Educational State University, Blagoveschensk V.Krushinski, I.Zalozhnih, A. Popov Ural Federal University, Kourovka A. Tlatov, A.V. Parhomenko, D. Dormidontov, V.Sennik Kislovodsk Solar Station of the Pulkovo Observatory Hugo Levato and Carlos Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) Claudio Mallamaci, Carlos Lopez and Federico Podest Observatorio Astronomico Felix Aguilar (OAFA) MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in Tunka was pointed to the GRB140129B 78 sec after notice time and 105 sec after trigger time at 2014-01-29 12:52:54 UT (Bernardini et al., GCN 15765). Such a long pointing time is due to internal mount pointing error under strong Siberian frost, which was automatically solved. A set of images with increasing exposures was obtained with the field at zenith distance 75 deg and setting. On our first (20s exposure) image we found optical transient at the SWIFT optical transient position. The unfiltered magnitude is about ~14m (Ivanov et al., GCN 15766). Our coordinates measured from the combination of 7 images are coincident with Swift UVOT position taking into account the error box reported by Bernardini et al., GCN 15765 and Swift-XRT position (Goad et al., GCN 15770): R.A. Dec. Err 21 47 01.71 +26 12 22.8 +/-0.5 arcsec The object is visible on 6 images, gradually fading below the detection limit on the 7th image. The results of our photometry are given in table below: T_start T-T_trig Tm-T_trig Exp,s Elevation Mag ---------------------------------------------------- 12:52:54 105 115 20 15.5 14.4 12:54:03 174 189 30 15.3 15.4 12:55:28 259 284 50 15.1 15.9 12:57:15 366 401 70 14.9 16.2 12:59:19 490 540 100 14.6 17.0 13:02:11 662 727 130 14.2 17.3 13:05:28 859 944 170 13.7 17.7 13:09:21 1091 1181 180 12.7 18.0 13:13:20 1330 1540 360 11.6 <18.4 # coadd 2 image In the table above 'T' is time of exposure beginning, 'Tm' is mid-exposure time. The power law slope is alpha = 1.42. The GRB140129B duration is small (T_90 < 2 sec, Palmer et al., GCN 15774), but spectrum is soft and this burst must be faint long GRB (Pal'shin, privet communication; Palmer et al., GCN 15774). Animation of seven frames by MASTER-Tunka is uploaded to http://master.sai.msu.ru/static/GRB/GRB140129B-MASTER-Tunka-anim.gif The light curve is available here: http://master.sai.msu.ru/static/GRB/GRB140129B_last.png Take the opportunity we would like to congratulate our first author from Siberia Vladimir Poleshchuk with the birth of the grandchild. The message may be cited.